Various throttle controls for lawnmowers, snow blowers, and similar power-operated equipment have been known, but such controls generally fail to meet one or more of the requirements of simplicity, low cost, quality, durability, ease of assembly and attachment, dependability, safety, smoothness of operation, and precision in the adjustment of engine speed. Typical throttle controls may be of the pivotal lever type as represented, for example, in U.S. Pat. Nos. 3,868,865 and 4,170,151, or of the sliding knob type as disclosed in U.S. Pat. No. 3,835,726. This invention is concerned with a throttle control of the slide type.
An objective of this invention is to provide a throttle control which overcomes the shortcomings of prior (and existing) controls and does so without substantially increasing material and manufacturing costs. Specifically, it is an object to provide a control assembly that consists essentially of two main components that may be easily installed upon the handle of a lawnmower or other power equipment and is reliable, durable, and safe in operation. When the control assembly is so installed, throttle settings are clearly and precisely indicated, an increasingly important requirement for controls to be used with engines of newer design. The "knob" of the control is actually a cover with an enlarged projection that may be easily gripped for slidably shifting the cover throughout its range of movement. Large bearing surfaces insure effective operation and, since they are concealed and protected by the cover, the risks that such surfaces might become damaged or worn are greatly reduced. A spring detent, also concealed and protected by the cover, provides the user with a tactile indication of engine settings and prevents unintended changes from those settings.
In brief, the control assembly takes the form of a mounting member that may be either cast, molded, or stamped and is adapted to be rigidly secured by bolt, screw, or rivet to the handle of a lawnmower or other similar equipment. The mounting member is supplied permanently connected to one end of a flexible tubular casing that slidably receives a throttle control wire, the wire having its opposite ends projecting beyond the ends of the tubular casing. The second component, the plastic cover, is provided with a small aperture for attachment to the end of the wire adjacent the mounting member and, when so connected, the cover is then simply snapped into position over the mounting member to conceal that member and its attachment to the equipment handle.
The cover is elongated and may be slid longitudinally upon the mounting member to vary engine operating speed. An arrow-shaped indicator formed as part of the mounting member protrudes through a slot in the cover, and markings upon the large exposed surface of the cover along the slot provide a clear indication of throttle settings. A protruding knob or projection, formed integrally with the cover, facilitates manual adjustment of the throttle control.
The mounting member includes a pair of longitudinal ribs that project laterally from its opposite sides, such ribs providing smooth upper and lower surfaces for sliding engagement with the cover. The cover in turn has its longitudinal side walls internally provided with elongated downwardly-facing bearing surfaces that slidably engage the upper surfaces of the ribs of the mounting member. Because of the extended length of the respective bearing surfaces and the fact that they are concealed and protected by the cover, problems of wear are virtually eliminated.
The cover is retained upon the mounting member by a plurality of lugs or barbs that project inwardly from the side walls of the cover beneath the ribs of the mounting member. The limited flexibility of the material from which the cover is made, the shape and dimensions of the cover, and the sloping surfaces of the lugs or barbs, permit the side walls of the cover to flex outwardly to accommodate the mounting member as the parts are fitted together and, once the cover is fully in place, to snap back into position and prevent subsequent removal of the cover. The detent means for the control assembly takes the form of one or more spring arms that are molded as integral parts of the cover and engage projections formed along one or both sides of the mounting member.
Other features, objects, and advantages will become apparent from the specification and drawings.